Composite door construction and method of making the same



INVENTOR. Fem/cvs f'. 5

2 Sheets-Sheet 1 F. E. LEE

COMPOSITE DOOR CONSTRUCTION AND METHOD OF MAKING THE SAME March 8, 1955 Filed Feb. 2s, 195o COMPOSITE DOOR CONSTRUCTION AND METHOD OF MAKING THE SAME Filed Feb'. 28, 1950 F. E. LEE

March 8, 1955 2 Shets-Sheet 2 R. N., my M N/..0 E. l W? f 15.. zu N M Cl. v.. B

United States Patent O COMPOSITE DOOR CONSTRUCTION AND METHOD OF MAKING THE SAME Francis E. Lee, Abington, Pa.,` assiguor to E. Raymond Snedaker, Ambler, Pa.

Application February 28, 1950, Serial No. 146,781

21 Claims. (Cl. 20 35) The present invention relates generally to composite ush type doors and the like and it relates more particularly to certain new and improved constructions for composite flush type nbre-panel doors and the like.

A11 object of the present invention is to provide a new and improved door construction. Another object of the present invention is to provide a door construction which is inexpensive, easy to construct and install, light in weight and yet strong, and which has excellent heat-insulation and sound-insulation properties, as well as good resistance to combustion and crushing; and a method of forming the same.

Still another object of the present invention is to provide an improved door construction composed of a flatsided panel or body of uncompressed cellulosic material having generally parallel spaced peripheral flanges, intermediate which is adhesively secured a continuous peripheral reinforcing frame composed of elongated snuglyfitting edge-strips of wood or the like, the panel or body having been surface-hardened by partial impregnation with a thermo-setting synthetic resin, or other binder capable of hardening under the action .of heat and pressure; the flanges being substantially fully impregnated and hardened by the heat-set resin or other binder.

Other objects and advantages of the present invention are apparent in the following detailed description, appended claims and accompanying drawings.

Generally speaking, the present invention contemplates a novel composite door (either one-ply or multi-ply) having a relatively ilat, rectangular form-retaining body of felted long-libre ligno-cellulosic material having thinwalled parallel transversely-spaced peripheral flanges or marginal portions, intermediate which are inserted elongated frame-members or edge-strips of wood or the like adapted to fit snugly within the grooves and optionally rigidly interconnected at their ends; the faces of the main panel (and, optionally, the inner sides of the anges) having been coated with a thermo-setting synthetic resin or other binder (capable of first penetrating and impregnating the main panel to a depth at least as great as the thickness of said marginal portions and thereafter hardening under the action of heat and pressure) and having subsequently been subjected to heat and pressure so as to form relatively smooth and hard outer surfaces on the panel and adhesively to secure the framemembers within the peripheral grooves of the main body portion.

For the purpose of illustrating the invention, there are shown in the accompanying drawings forms thereof which are at present preferred, although it is to be understood that the various instrumentalities of which the invention consists can be variously arranged and organized and that the invention is not limited to the precise arrangements and organizations of the instrumentalities as herein shown and described.

Referring to the accompanying drawings in which like reference characters indicate like parts throughout:

Figure 1 represents a perspective view of a door constituting one embodiment of the present invention; parts being broken away better to reveal the construction thereof.

Figure 2 represents a horizontal cross-sectional view, on an enlarged scale, taken generally along the line 2 2 of Figure l.

Figure 3 represents a fragmentary perspective View 8 showing another embodiment of the present invention.

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Figure 4 represents a horizontal cross-sectional view taken generally along the line 4 4 of Figure 3.

Figure 5 represents a horizontal cross-sectional view generally like that of Figure 4 but showing still another embodiment of the present invention.

Figure 6 represents a fragmentary perspective view of a still further embodiment of the present invention.

Figure 7 represents a horizontal cross-sectional view taken generally along the lines 7 7 of Figure 6.

Figure 8 represents a fragmentary side elevational view of a door constituting another embodiment of the present invention.

Figure 9 represents a perspective view of still another embodiment of the present invention; parts being broken away better to reveal the construction thereof.

Figure l0 represents a horizontal cross-sectional View generally along the line 10 10 of Figure 9.

Figure ll represents a vertical cross-sectional view generally along the line 11 11 of Figure 9.

In Figure 1, there is shown a composite door forming one embodiment of the present invention which includes a one-piece main panel or body 10 which is relatively at and which has a rectangular contour corresponding generally to the size and shape of the linal door.

The main panel or body 10 is formed of partially-compressed long-iibre felted ligno-cellulosic material. The term ligno-cellulosic material comprehends mechanically-produced or chemically-produced or mechanicallyand-chemically-produced fibres of woody material containing the greater part of its lignin content, including but not limited to wood fibres, corn stalks, sugar cane stalks and the like, capable of being formed into formretaining felted sheets or panels. A minor proportion (i. e. less than half) of fibrous mineral material (as for example asbestos) may also be incorporated, and, as used in the appended claims, the expression felted ligno-cellulosic iilaterial is intended to comprehend this modification as we The main panel or body 10 is initially of relatively soft felted texture which has been compressed only slightly (i. e. just enough to make it form-retaining) and is relatively light in weight (with a density of approximately 8-20 pounds per cubic foot). The material sold commercially by Minnesota & Ontario Paper Company under the name Insulite is especially well suited for this purpose. Other commercially available materials can also be employed, as for example Celotex (manufactured by the Celotex Corp). After being cut to desired size, the main panel or body 1s rabbeted or routed out along each of its peripheral edges to form parallel-sided communicating top and bottom grooves 11 and 12 respectively and side grooves 13 and 14. All of the grooves 11-14 are preferably uniform 1n transverse (i. e. front-to-back) dimensions and the top and bottom grooves 11 and 12 are preferably uniform 1n depth. However, one of the side grooves (as for example groove 13) has a greater depth than the other side groove (as for example groove 14), f or reasons which will be apparent hereinbelow.

The transverse dimension of the grooves 11-14 is appreciably greater than half the thickness of the panel 10 so as to provide relatively thin-walled transverselyspaced parallel'anges or marginal portions. That is, the groove 11 1s delined by parallel transversely-spaced flanges or marginal portions 11-a and 11-b and a bottom wall 11-c. Similarly, the groove 12 is dened by flanges 12-a and 12-11 and by bottom wall 12 c; the groove 13 by flanges 13-a and 13-b and bottom wall 13-c; and goove 14 by anges 141-0 and 14-b and bottom Wall The grooves 11, 12, 13 and 14 are constructed and arranged snugly to receive solid frame-members or edgestrlps 1S, 16, 17 and 18 respectively. The strips 15-18 are formed of Wood (as for example oak or pine) and are preferably rectangular in cross-section with generally the same transverse dimension and depth as the grooves into which they are to be fitted.

The frame-members 17 and 18 may extend the entire length of their grooves (13 and 14) while the framemembers 15 and 16 may be shorter in length than the grooves 11 and 12 by the combined depths of the members 17 and 18, as indicated in Figure 1. In other words, the top and bottom frame-members 15 and 16 extendy intermediate the bottom walls 13-c and 14-c of the side grooves 13 and 14.

It is apparent, however, that the frame-members or edge-strips 15 and 16 could be lengthened to extend the entire length of the grooves 11 and 12 and that the framemembers or edge-strips 17 and 18 could be correspondingly shortened to extend only intermediate the walls 11-c and 12-c.

One or more dowel-pins 19 immovably connect the abutting ends of the frame-members or edge-strips 15-18 so as to form them into a more or less integral frame having appreciably greater structural strength and rigidity than the panel 10.

After the frame-members 15-18 have been positioned within the grooves 11-14, as described above, the sides 20 and 21 of the main panel or body 10 are coated with any suitable thermosetting synthetic resin, as for example Resinox #468 (which is an approximately 50% solution of a water-soluble phenol-formaldehyde resin manufactured by Monsanto Chemical Company).

If desired, the synthetic resin may be provided with a small amount (for example 1%) of any suitable wetting agent, as for example Triton X-IO() (which is alkyl aryl polyether alcohol manufactured by Rohm & Haas Company).

A minor proportion of ethyl alcohol or other appropriate compatible diluent may be added to the synthetic resin in order to improve uniformity and ease of penetration.

The coated panel or body 10 is then heated in any suitable press, between two flat platens until the resin has hardened or set, the fibres in the impregnated zones 20-a and 21-a being somewhat compressed during this operation.

As indicated particularly in Figure 2, the resin penetrates the fibre panel or body to a depth somewhat greater than the thickness of the ianges 11-a, 11-b, 12-a, 12-b, 13-a, 13-b, 14-a and 14-b. However, the total penetration (on both sides) should preferably be less than half the total thickness of the panel or body 10. For example, if the total thickness of the panel 10 is 1%, each of the anges may be 1A thick and the depth of penetration, on each side of the panel 10, may be 1%.

This complete penetration of the flanges enables the resin to reach the sides of the wooden strips 15-18, so that setting or hardening of the resin, after impregnation, results in an adhesive bond between the strips 15-18 and the sides of grooves 11-14, sutiiciently strong to maintain the strips securely in place within the grooves and to prevent shifting or displacement of the strips.

This complete penetration of the groove flanges for at least a substantial distance inward from the edges of the main panel or body 10, results in a nal structure of great peripheral strength since the impregnated flanges and the intervening wooden strips provide a relatively tough and durable area extending inward a substantial distance (for example l to 3") along each side of the edges of the door, which, of course, are the zones of the greatest wear and stress.

The cementing action of the hardened-in-situ resin also results in a tirm interconnection between the ends of the strips 15-18 and, indeed, this cementing action may be suicient, under some circumstances, to permit elimination of the dowel pins 19.

It has been found that the provision of groove-tianges having substantially uniform thickness (i. e. anges with substantially parallel sides) for at least an appreciable distance inward from the outer edges of the main panel, 10 results in a structure of great strength.

Instead of providing dowel-pins 19 to connect the ends of the frame members 15-18, it is possible to fasten them together in other ways, as for example by providing tongue-and-groove connections, by using wood-glue, etc.

The extra width of the side frame-member or edgestrip 17 permits the insertion of a door-handle and/or lock unit.

Another embodiment of the present invention is shown in Figures 3 and 4. In this embodiment, the body 10-a, instead of being formed from a single sheet of soft fibrous material (as in the embodiment of Figures l and 2) is formed from a pair of thinner sheets. disposed in side-by-side relationship.

While it is possible preliminarily to press the sheets making up the body 10-a together (optionally, employing a thermo-setting synthetic resin coating or any other suitable adhesive material on the adjoining surfaces of the two sheets to give firmer adhesion) into a more or less unitary structure which can then be peripherally grooved or rabbeted and otherwise treated in a manner similar to that described in connection with the embodiment of Figures 1 and 2, I prefer to rabbet the halves of the body 10-a individually along their adjoining edges (so that, when the halves are subsequently placed side-byside, the U-shaped grooves shown in Figure 4 will be formed) and then to place the rabbeted sections sideby-side so as to enclose the edge-strips, etc. The sides 20 and 21 are then coated with thermo-setting synthetic resin (which may also be applied to the adjoining faces of the sheets making up the body lil-a) and the composite structure is pressed between the flat platens of a heated press to effect interconnection of the halves of the body 10-a simultaneously with the hardening of the sides 20 and 21 and the adhesion of the edge-strips 15-18, etc.

In this embodiment, instead of having the grooves 11-15 meet each other at right angles (as in the embodiment of Figures 1 and 2), the main panel or body 10-a is provided with four diagonal corner grooves 22 (of which only two are shown in Figure 3; the other two being identical) which are constructed and arranged to receive triangular corner insert-members 23 adapted to underlie and support the ends of the frame-members or edge-strips 15-18 and thereby to increase the structural strength of the frame and the door.

In this embodiment, the walls 11-11, 11-b, 11-c, 12-a, 12-b, 12-c, 13-a, 13-b, 13-c, 14-a, 14-b and 14-c of the grooves 11-14, as well as the side walls 22-a and 22-b and the bottom walls 22-c of the corner grooves 22 are coated with Resinox or other thermo-setting synthetic resin before insertion of the corner insert-members 23 and the edge-strips 15-18 so that when the door is completed in the manner described hereinabove in connection with the embodiment of Figures l and 2 (i. e. by coating the sides 20 and 21 with thermo-setting synthetic resin and subsequently pressing between two flat platens of a heated press), the resin will penetrate inward from the groove-walls and harden, as indicated at 24 in Figure 4, to effect a cementing or adhesion of the corner insertmembers 23 and the edge-strips 15-18 to the main panel or body lil-a, without having to rely upon penetration of resin from the sides 20 and 21.

Instead of applying the resin to the walls of thc grooves, I may apply it to the walls of the corner insert-members 23 and the edge-strips 15-18 since, when the so-coated corner insert-members and edge-strips are inserted within the grooves, the coating will adhere to the groove-walls and results in penetration and hardening during the heating operation. The coating of the corner insert-members 23 and the edge-strips 15-18 also results in adhesion along the adjoining surfaces 25 thereof.

Instead of relying on a resin coating to effect adhesion along the adjoining surfaces 25 of the edge-strips and corner-inserts, I may coat these surfaces with wood-glue or other conventional mucilaginous material. Alternatively, I may interconnect the edge-strips 1:318 and the corner insert-members 23 by use of dowel-pins or the like in a manner analogous to that shown in the embodiment of Figures 1 and 2.

I may eliminate the coating of the groove-walls, in the embodiment of Figures 3 and 4, and rely solely upon the resin penetrating inward from the sides 20 and 21 in a manner analogous to that shown and described in connection with the embodiment of Figures l and 2.

Similarly, I may modify the embodiment of Figures l and 2 by providing supplementary resin coating for the groove-walls in a manner analogous to that described in connection with the present embodiment.

In the embodiment shown in Figure 5, thin outer face sheets or panels 26 and 27 are provided for the sides 20 and 21 of the main panel or body 10. The facing sheets or panels may be of relatively thin wood veneer of jA43" or 1,@8" thickness, or such decorative laminus as Foi-mica" or Micarta etc.

The facing sheets 26 and 27 are placed in position after the sides 20 and 21 of the main panel or body l() are coated with the thermo-setting synthetic resin and the three sheets (i. e. the main panel or body 10 and the panels 26 and 27 on either side thereof) are placed bctween the fiat platens of the heated press. In this way, hardening of the synthetic resin coating on the sides 20 and 21 causes the facing sheets 26 and 27 to adhere thereto, as part of the same treating operation.

Alternatively, the facing strips 26 and 27 can be affixed in a subsequent operation (i. e. after impregnation and heat-setting of the sides 20 and 21 of the main panel or body 10) by simply applying an additional coating of thermo-setting synthetic resin to the hardened sides 20 and 21, placing the facing strips 26 and 27 in position and pressing the three-ply structure between the flat platens of a heated press.

In the embodiment shown in Figures 6 and 7, facing sheets or panels 28 and 29 of multi-ply wood veneer or plywood are employed.

In this embodiment, the edge flanges of the main panel or body 10 are made slightly smaller and the edge-strips are provided with small shoulders 30 at their outer edges. The shoulders 30 have the same thickness as the groove flanges and overlie the outer edges thereof so as to abut the peripheral edges of the facing sheets 28 and 29. In this way, a wood-to-wood peripheral support is provided for the facing sheets along the edges of the door. That is, instead of having intervening layers of impregnated fibrous material intermediate the edge strips and the facing sheets (as in the embodiment of Figure this embodiment has continuous wood-to-wood surfaces at all of the edges of the door.

The facing sheets 28 and 29 can be applied in either of the ways described in connection with the embodiment of Figure 5. That is, the aixation of the facing strips and the hardening of the surfaces 20 and 21 can be effected in a single treatment between the flat platens of a heated press; the hardening of the resin causing the facing sheets to adhere to the surfaces 20 and 21. In stead, the surfaces 20 and 21 can first be hardened with the thermo-setting synthetic resin and, thereafter, additional binder or resin can be applied to the hardened surfaces 20 and 21 to cement the sheets 28 and 29 thereto.

In the embodiment of Figures 6 and 7, the left-hand groove 13 and the corresponding edge-strip 17 are made smaller in depth and a separate wooden lock-receiving insert-block or lock-rail 32 is provided adjacent the inner edge of the strip 17; a suitable recess being cut in the main panel or body to accommodate the insert block 32. The block 32 will be held in place by the resin contained in the impregnated fibrous flanges flanking the block 32, which resin will form an adhesive bond between the fibrous flanges and the block, and may also be further secured to the adjoining edge-strip either by the same resin or by a wood-glue or other adhesive applied between the block and the edge-strip and may also be doweled to the edge-strip.

In place of the Resinox, I may employ other phenolformaldehyde resins which are commercially available, as, for example, Amberlite PR-14 of Rohm & Haas Co.

I may also employ other thermo-setting synthetic resins, such as urea formaldehyde resins and melamine formaldehyde resins.

I may also employ various theme-setting natural resins as the impregnating material and, accordingly, the expression thermo-setting resinous binder as used in the appended claims is intended to comprehend all synthetic or natural resins which can be applied in liquid form (i. e. as solutions, suspensions, dispersions, etc.) and which are capable of penetrating the soft brous material to an appreciable extent and which are capable of hardening in situ under the action of heat and pressure to form a relatively hard, continuous outer layer or skin of considerably greater density and strength than the fibrous material itself.

The penetration or impregnation of the fibrous material by the thermo-setting resinous binder is a graded or graduated one, the hardness, density and extent of impregnation gradually diminishing from the outside toward the inside of the fibrous panel or body. As pointed out above, however, the total thickness of the impregnated area is preferably less than half of the total thickness of the main body or panel so as to keep the weight and cost of the final door as low as possible.

The novel door construction of the present invention is light in weight and yet strong, rigid and capable of withstanding severe impacts and hard usage.

The hinges are fastened to one of the edge-strips and the continuous wooden frame provided by the edgestrips (especially when they are rigidly connected to each other by dowel-pins or the like) provides for more uniform Weight-distribution with smaller load on the center fibrous core.

The edges of the door can be shaved or otherwise trimmed where necessary to fit variations in doorway sizes. The use of groove-flanges which are relatively parallel and of uniform thickness permits the shaving off of some of the edge material of the door without in any way affecting the bond between the edge strips and the groove-walls.

The final coated surface can be painted or stained or varnished in any conventional manner.

Instead, the thermo-setting synthetic resin or the like can itself be pigmented or otherwise appropriately colored so that the door will be ready to hang after the heatsetting operation.

Where separate facing panels are employed on the sides of the main panel 10, these panels can be pigmented or painted or the like either prior to or subsequent to theoperation whereby they are adhesively secured to the main panel.

The coating or skin of synthetic resin renders the door relatively fire-resistant while the central unimpregnated core of soft fibrous material imparts good soundproofing characteristics to the door as well as giving the door effective heat-insulation properties.

The door construction of the present invention, unlike commonly used fir paneling, is not materially affected by moisture or other weathering elements.

In Figure 8 there is shown another embodiment of the present invention which generally resembles the embodiment of Figures l and 2 except as described hereinbelow.

Thus, the edge-strip 17 of the embodiment of Figure 8 is made smaller in horizontal dimension so as to correspond generally to the edge-strip 18.

The main panel 10 is provided with rounded notches 33 and 34 which extend inwardly from the bottom walls 13-c and 14-0 of the side grooves 13 and 14 respectively (the notches 33 and 34 being centered vertically with respect to the panel 10) and are constructed and arranged to receive rounded insert-blocks or lock-rails 35 and 36 respectively of wood or the like.

As in the embodiment of Figure 6, either of the insert blocks can be adapted to receive any conventional metal handle-and-lock unit. The provision of two separate insert blocks 35 and 36 enables the door to be hung either as a left-hand door or as a right-hand door withollllt the need for reversing the top and bottom edges as we The insert blocks 35 and 36 are generally the same in thickness (i. e. front-to-rear dimension) as the edgestrips 17 and 18 and may be adhesively secured thereto along their adjoining surfaces 37 and 38 by means of wood-glue or any other suitable adhesive material.

The insert blocks 35 and 36 are held in place within the notches 33 and 34 by the Resinox or other thermosetting synthetic resin which is coated on the walls of the notches or on the Walls of the insert blocks and which thereafter hardens-in-situ during the final sidehardening operation which is similar to that described hereinabove in connection with the embodiments of Figures l and 2.

Synthetic resin can also be employed, instead of woodglue, to effect adhesion of the insert blocks 35 and 36 to the edge-strips 17 and 18 along the adjoining surfaces 37 and 38.

If it is desired, however, the coating of the notches 33 and 34 or the insert blocks 35 and 36 can be omitted and, instead, the adhesive bond between the notch walls and the insert blocks can be effected by the resin penetrating inward from the coated side walls of the main panel 10 in a manner similar to that described hereinabove in connection with the embodiment of Figures 1 and 2.

Rounding of the notches 33 and 34 simplifies their construction since it permits them to be cut with a conventional milling machine or the like.

The insert blocks 35 and 36 may have a vertical dimension of about 12 inches and a depth of about 31/2 inches so that, if the edge-strips are approximately 1% inches, the total depth of wood at the lock-receiving areas is approximately inches (measured inward from the side edges of the door).

In Figures 9-11, there is shown still another embodiment of the present invention wherein the body is composed of a relatively thick center panel 40 of felted ligno-cellulosic material and a pair of relatively thin side panels 41 and 42 also of felted ligno-cellulosic material, the side panels 41 and 42 having been hardened and adhesively secured to the center panel 40 in a manner to be described hereinbelow.

As indicated particularly in Figures l0 and ll, the side panels 41 and 42 are somewhat greater, in both horizontal and vertical dimension, than the center panel 40 so that relatively thin generally parallel spaced-apart flanges are formed.

Thus, as indicated in Figure l0, flanges 43 and 44 extend outward beyond the left-hand edge 45 of the center panel 40 while flanges 46 and 47 extend outward beyond the right-hand edge 48 of the center panel 40. As shown in Figure l1, flanges 49 and 50 extend upward beyond the upper edge 51 of the center panel 40 while flanges 52 and 53 extend downward beyond the lower edge 54 of the center panel 40.

Disposed within the grooves thus formed by the peripheral flanges, are four snugly-fitting edge-strips 55, 56, 57 and 58 of wood or the like which form a recessed generally continuous frame or border, the ends of the upper and lower edge strips 57 and 58 abutting the ends of the left and right edge strips 55 and 56 and, preferably, being secured thereto by wood glue (or other adhesive material) or by dowel-pins or other mechanical interconnecting elements (not shown).

Rounded slots 59 and 60 are milled out or otherwise formed generally centrally of the side edges 45 and 48, respectively, of the center panel 40, the slots 59 and 60 being constructed and arranged to receive insert-blocks or lock-rails 61 and 62, respectively, of wood or the like.

In constructing the embodiment of Figures 9-11, I first Cut the panels 40, 41 and 42 to size and then formed the slots 59 and 60.

The wood edge-strips 55, 56, 57 and 58 and the insert-blocks 61 and 62 are then cut to size.

The insert-blocks 61 and 62 are then positioned within the slots 59 and 60 and the edge-strips 55, 56, 57 and 58 are positioned adjacent the edges 45, 48, 51 and 54 of the main panel 40. Where the edge-strips are connected at their ends, this can be done preliminarily to form a more or less unitary frame into which the main panel 40 can be fitted.

An appropriate adhesive is applied to the juxtaposed surfaces of the edge-strips and the main panel, by coating either the edge-strips or the edges of the main panel or both. Similarly, the juxtaposed surfaces of the insert-blocks 61 and 62 and of the slots 59 and 60 can be coated with an adhesive material. So, too, the juxtaposed surfaces of the edge-strips 55 and 56 and the insert-blocks 61 and 62 can be provided with wood-glue or any other appropriate adhesive material.

Both sides of each of the panels 41 and 42 are then coated with Resinox or other thermo-setting resinous binder in liquid form.

The coated panels 41 and 42 are then arranged in side-by-side relationship to the center panel 40 and the edge-strips after which the entire assembly is subjected to the action of heat and pressure between the flat platens of a heated press.

The main panel 40 is initially made slightly greater in thickness than the edge-strips so that it will be compressed slightly to generally the same thickness as the edge-strips under the action of the press.

The coatings of Resinox or the like penetrate the side panels 41 and 42 completely and also penetrate a slight distance into the main panel 40 so that, when the Resinox hardens or sets under the action of the heat, the side panels 41 and 42 are hardened throughout and are also adhesively secured to the entire panel 40 as well as to the edge strips 55, 56, 57 and 58.

In other words, each of the side panels 41 and 42 forms a more or less uniform hardened skin or outer surface for the door which is relatively strong and fireresistant.

The flanges 43, 44, 46, 47, 49, 50, 52 and S3 are also hardened in situ to provide strong supporting surfaces for the edge-strips 55, 56, 57 and 58 so that the 8 composite door is formed into a relatively strong more or less integral unit.

The inner unimpregnated portion of the center panel 40 imparts effective sound proofing and insulation properties to the door.

The adhesive applied to the juxtaposed surfaces of the center panel 40, the edge-strips 55, 56, 57 and 58 and the insert blocks 61 and 62 can, optionally, be Resinox or other thermo-setting resinous binder which will harden-in-situ under the action of the heat and pressure.

The final door can be used as a left-hand or as a right-hand door by installing an appropriate metal handle-and-lock unit (not shown) in one of the insert blocks 61 and 62 and by mounting hinges on the opposite'edge of the door.

The hardened side panels 41 and 42 can be painted or otherwise suitably finished in conventional manner or, instead, the pigmentation can be effected by incorporating any suitable color in the resinous binder.

By way of illustration only, the thickness of the center panel and the edge-strips in the final door can be of the order of ll/s" (although, as mentioned above, the initial thickness of the center panel should be slightly greater to permit'some compression during the forming operation). Each of the side panels 41 and 42 can be of the order of W16" to -l/. The edge-strips can be about ll/z" in depth while the insert-blocks can be about 31/2" in depth, l2 in height and 1%" in thickness.

These dimensions can, of course, be varied as desired.

I prefer, however, to keep the combined thicknesses of the side panels 41 and 42 appreciably less than the final thickness of the center panel 40 and preferably less than half the final thickness of the center panel 40.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiments be considered in all respects as illustrative and not restrictive, reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

I may also impress the door with panel-like depressions on one or both sides, simultaneously with the aforesaid pressing operation. This can be done by providing the press-platten or plattens with raised portions corresponding to the panel effect desired.

Having thus described my invention, I claim as new and desire to protect by Letters Patent the following:

l. A composite construction for a door or the like comprising a generally flat-sided rectangular body of felted llgno-cellulosic material having a pair of spaced relatively thin generally parallel flanges formed along each of its edges, generally rigid snugly-fitting edge-strips immovably disposed intermediate said flanges, the ends of said edge-strips contacting each other to form a generally continuous recessed border, the sides of said body being compressed and impregnated with a hardened-in-situ thermo-setting resinous binder to a depth generally equal to the thickness of said flanges, whereby said flanges are fully impregnated with said hardened-in-situ thermo-setting resinous binder to provide relatively strong supporting surfaces for said edge-strips.

2. A composite construction for a door or the like comprising a generally flat-sided rectangular body of felted ligno-cellulosic material having a pair of spaced relatively thin generally parallel flanges lformed along each of its edges, snugly-fitting edge-strips of wood or the like disposed intermediate said flanges. the ends of said edgestrips contacting each other to form a generally continuous recessed border, the sides of said body being compressed and impregnated with a hardened-in-situ thermo-setting resinous binder to a depth at least equal to the thickness of said flanges, whereby said flanges are fully impregnated with said hardened-in-situ thermo-setting resinous binder to provide relatively strong supporting surfaces for said edge-strips, the binder serving adhesvely to hold said edge-strips intermediate said flanges.

3. A composite construction for a door or the like comprising a generally flat-sided rectangular body of felted ligno-cellulosic material having a pair of spaced relatively thin generally parallel flanges formed along each of its sides, snugly-fitting edge-strips of wood or the like disposed intermediate said tlanges, the ends of said edge-strips contacting each other to form a generally continuous recessed border, the sides of said body being compressed and impregnated with a hardened-in-situ thermo-setting resinous binder to a depth generally equal to the thickness of said flanges, whereby said flanges are fully impregnated with said hardened-in-situ thermo-setting resinous binder to provide strong supporting surfaces for said edge-strips, and a pair of thin facing sheets of relatively harder material substantially co-extensive with and adhesively secured to the sides of said main panel.

4. A composite construction for a door or the like comprising a generally flat-sided rectangular body of felted ligno-cellulosic material having a pair of spaced relatively thin generally parallel flanges formed along each of its sides, snugly-fitting edge strips of wood or the like adhesively secured intermediate said flanges, the ends of said edge-strips contacting each other to form a generally continuous recessed border, the sides of said body being compressed and impregnated with a hardened-insitu thermo-setting resinous binder to a depth generally equal to the thickness of said flanges, whereby'said flanges are fully impregnated with said hardened-in-situ thermosetting resinous binder to provide relatively strong supporting surfaces for said edge-strips.

A composite construction for a door or the like comprising a generaly flat-sided rectangular panel of felted ligno-cellulosic material having a pair of spaced relatively thin generally parallel flanges formed along each of its edges, snugly-fitting edge-strips of wood or the like adhesively secured intermediate said flanges, the ends of said edge-strips contacting each other to form a generally continuous recessed border, the sides of said panel being compressed and impregnated with a hardened-in-situ thermosetting resinous binder to a depth generally equal to the thickness of said flanges, whereby said flanges are fullyimpregnated with said hardened-in-situ thermo-setting resinous binder to provide relatively strong supporting surfaces for said edge-strips, the central unimpregnated zone of said panel constituting more than half the total thickness of said panel and having a density of about 8-20 pounds per cubic foot, the other impregnated zones of said panel having an appreciable greater density.

6. A composite construction for a door or the like comprising a generally flat-sided two-ply rectangular body of felted ligno-cellulosic material having a pair of spaced relatively thin generally parallel flanges formed along each of its edges, snugly-fitting edge-strips of wood or the like disposed intermediate said flanges, the ends of said edgestrips contacting each other to form a generally continuous recessed border, the sides of said body being compressed and impregnated with a hardened-in-situ thermosetting resinous binder to a depth generally equal to the thickness of said flanges, whereby said flanges are fully impregnated with said hardened-in-situ thermo-setting resinous binder to provide relatively strong supporting surfaces for said edge-strips.

7. A composite construction for a door or the like cornprising a generally flat-sided rectangular panel of felted ligno-cellulosic material having a pair of spaced relatively thin generally parallel flanges formed along each of its edges, snugly-fitting edge-strips of wood or the like adhesively secured intermediate said flanges, the ends of said edge-strips contacting each other to form a generally continuous recessed border, the sides of said panel being compressed and impregnated with a hardened-in-situ thermo-setting resinous binder to a depth generally equal to the thickness of said flanges, whereby said flanges are fully impregnated with said hardened-in-situ thermo-setting resinous binder to provide relatively strong supporting surfaces for said edge-strips, the density and extent of impregnation of the sides of said panel gradually diminishing inwardly.

8. A composite construction for a door or the like comprising a generally flat-sided rectangular body of felted ligno-cellulosic material having a pair of spaced relatively thin flanges formed along each of its edges, snuglyfitting edge-strips of wood or the like adhesively secured intermediate said flanges, the ends of said edge-strips contacting each other to form a generally continuous recessed border, the sides of said body being compressed and irnpregnated with a hardened-in-situ thermo-setting resinous binder to a depth sufficient to ensure complete penetration of said flanges throughout an area extending an appreciable distance inward from the outer edges thereof, thereby to provide relatively strong supporting surfaces for said edge-strips.

9. A composite construction for a door or the like comprising a generally flat-sided rectangular two-ply body of felted ligno-cellulosic material having a pair of spaced relatively thin flanges, snugly-fitting edge-strips of wood or the like disposed intermediate said flanges, the ends of said edge-strips contacting each other to form a generally continuous recessed border, the sides of said body being compressed and impregnated with a hardened-in-situ thermo-setting resinous binder to a depth sufficient to ensure complete penetration ofl said flanges throughout an area extending an appreciable distance inward from the outer edges thereof, thereby to provide relatively strong supporting surfaces for said edge-strips, the binder serving adhesively to hold said edge-strips intermediate the flanges.

l0. A method of making a composite door or the like which comprises forming a generally rectangular body of felted ligno-cellulosic material having generally flat sides` peripherally grooving said body to provide spaced relatively thin generally parallel flanges, positioning within said flanges snugly-fitting edge-strips of wood or the like, the ends of said edge-strips contacting each other to form a generally continuous recessed border, coating the sides of said body with a thermo-setting resinous binder in liquid form, and subjecting the coated sides to the action of heat and pressure so as to compress the body and to cause said resinous binder to penetrate said body to a depth generally equal to the thickness of said flanges and thereafter to harden-in-situ thereby to provide relatively strong supporting surfaces for said edge-strips and to provide relatively hard and dense surfaces upon the sides of said body.

ll. A method of making a composite door or the like which comprises forming a generally rectangular body of felted ligno-cellulosic material having generally flat sides, peripherally grooving said body to provide spaced relatively thin generally parallel flanges, positioning within said flanges snugly-fitting edge-strips of wood or the like, the ends of said edge-strips contacting each other to form a generally continuous recessed border, coating the sides of said body with a thermo-setting resinous binder in liquid form, and subjecting the coated sides to the action of heat and pressure so as to compress the body and to cause said resinous binder to penetrate said body to a depth at least equal to the thickness of said flanges and thereafter to harden-in-situ thereby to provide relatively strong supporting surfaces for said edge-strips and to provide relatively hard and dense surfaces upon the sides of said body, the binder serving adhesively to hold said edgestrips withirrthe grooves.

l2. A method of making a composite door or the like which comprises forming a generally rectangular body of felted ligne-cellulosic material having generally flat sides, peripherally grooving said body to provide spaced relatively thin generally parallel flanges, adhesively securing within said flanges snugly-fitting edge-strips of wood or the like, the ends of said edge-strips contacting each other to form a generally continuous recessed border, coating the sides of said body with a thermo-setting resinous binder in liquid form, and subjecting the coated sides to the action of heat and pressure so as tocompress the body and to cause said resinous binder to penetrate said body to a depth generally equal to the thickness of said flanges and thereafter to harden-in-situ thereby to provide relatively strong supporting surfaces for said edge-strips and to provide relatively hard and dense surfaces upon the sides` of said body.

13. A method of making a composite door or the like which comprises forming a main panel of felted lignocellulosic material having generally flat sides, peripherally grooving said panel to provide spaced relatively thin generally parallel flanges, adhesively securing within said flanges snugly-fitting edge-strips of wood or the like, the ends of said edge-strips contacting each other to form a generally continuous border, coating the sides of said main panel with a thermo-setting resinous binder in liquid form, positioning a pair of thin facing sheets of relatively harder material against said coated sides, and subjecting the assembly to the action of heat and pressure, so as to cause the fibres of said panel to be compressed and impregnated with the thermo-setting resinous binder to a depth generally equal to the thickness of said flanges; the resin subsequently hardening-in-situ so as to provide relatively strong supporting surfaces ,for said edge-strips and relatively hard outer skins on said sides and at the same time adhesively to secure said facing sheets to said sides.

14. A method of making a composite door or the like which comprises forming a generally rectangular body of felted ligno-cellulosie material having generally flat sidesVperipherally grooving said body to provide spaced relatively thin generally parallel flanges, positioning within said flanges snugly-fitting edge-strips of wood or the like, with coatings of thermo-setting resinous binder intervening said edge-strips and the flanges, the ends of said edge-strips contacting each other to form a generally continuous recessed border, coating the sides of said body with a thermo-setting resinous binder in liquid form, and subjecting the coated sides to the action of heat and pressure so as to compress the body and to cause said resinous binder to penetrate said body to a depth generally equal to the thickness of said flanges and thereafter to harden-in-situ thereby to provide relatively strong supporting surfaces for said edge-strips and to provide relatively hard and dense surfaces upon the sides of said body, the resinous binder intervening the edgestrips and the llanges also hardening-in-situ during the last-mentioned operation, thereby to secure said edgestrips intermediate said flanges.

15. A method of making a composite door or the like which comprises forming a rnain panel of felted lignocellulosic material having generally ilat sides, peripherally grooving said panel to provide spaced relatively thin generally parallel flanges, positioning within said flanges snugly-fitting edge-strips of wood or the like, the ends of said edge-strips contacting each other to form a generally continuous border, coating the sides of said main panel with a thermo-setting resinous binder in liquid form, and subjecting the coated sides to the action of heat and pressure so as to compress the panel and to cause said resinous binder to penetrate said panel to a depth generally equal to the` thickness of said flanges and thereafter to harden-in-situ thereby to provide relatively strong supporting surfaces for said edge-strips and to provide relatively hard and dense surfaces upon the sides of said panel and subsequently adhesively securing a pair of thin facing sheets of relatively hard material to the sides of said main panel.

16. A method of making a composite door or the like which comprises peripherally rabbeting each of a pair of generally identical flat-sided rectangular panels of felted ligno-cellulosic material, positioning said panels in side-by-side relationship with the rabbeted edges forming a peripheral U-shaped groove defined by spaced relatively thin generally parallel flanges and with snuglyfitting edge-strips of wood or the like disposed within the grooves and extending intermediate the flanges, the ends of said edge-strips contacting each other to form a generally continuous border, coating the outer sides of l said panels with a thermo-setting resinous binder in liquid form, and subjecting the coated sides to the action of heat and pressure so as to cause the panels to adhere to each other and to cause the resinous binder to penetrate the panels to a depth equal to the thickness of the flanges and thereafter to harden-in-situ thereby to provide relatively strong supporting surfaces for said edgestrips and to provide relatively hard and dense surfaces upon the sides of said panels, the binder also adhesively securing the edge-strips to the flanges.

17. A method of making a composite door or the like which comprises peripherally rabbetng each of a pair of generally identical flat-sided rectangular panels of felted ligne-cellulosic material, applying a coating of adhesive material to one side of at least one of said panels, positioning said panels in side-by-side juxtaposition with the coated side innermost and with the rabbeted edges forming a peripheral U-shaped groove defined by spaced relatively thin generally parallel flanges and with snuglyfitting edge-strips of wood or the like disposed within the grooves and extending intermediate the flanges, the ends of said edge-strips contacting each other to form a generally continuous border, the contiguous surfaces of said edge-strips and said grooves being coated with an adhesive material, coating the outer sides of said panels with a thermo-setting resinous binder in liquid form, and subjecting the coated sides to the action of heat and pressure so as to cause the panels to adhere to each other and to cause the resinous binder to penetrate the panels to a depth equal to the thickness of the flanges and thereafter to harden-in-situ thereby to provide relatively strong supporting surfaces upon the sides of said panels, said adhesive material hardening during the last-mentioned operation thereby to secure the edge-strips intermediate the flanges.

18. A method of making a composite door or the like which comprises forming a generally rectangular body of felted ligno-cellulosic material having generally flat sides and having a pair of spaced relatively thin generally parallel flanges formed along each of its edges, adhesively securing intermediate said flanges a plurality of elongated edge-strips of wood or the like so that the ends of said edge-strips contact each other to form a generally recessed border for said body, coating the sides of said body with a thermo-setting resinous binder in liquid form, and subjecting the coated sides to the action of heat and pressure so as to compress the body and to cause said resinous binder to penetrate said body to a depth generally equal to the thickness of said flanges and thereafter to hardenin-situ thereby to provide relatively strong supporting surfaces for said edge-strips and to provide relatively hard and dense surfaces upon the sides of said body.

19. A composite construction for a door or the like comprising a generally flat-sided rectangular center panel of felted ligno-cellulosic material, a pair of relatively thin flat-sided rectangular side panels of felted ligno-cellulosic material disposed on either side of said center panel, said side panels being larger than said center panel in length and width so as to provide a pair of outwardly-protruding relatively thin generally parallel spaced flanges along each of the edges of the main panel, a plurality of snugly-fitting elongated edge-strips of wood or the like adhesively secured intermediate said flanges and forming a generally Continuous recessed frame or border for the door, said side panels and ilanges being fully impregnated with a hardened-in-situ thermo-setting resinous binder thereby to provide relatively hard outer surfacing for the door and to provide relatively strong supporting surfaces for thc edge-strips, said resinous binder also serving adhesively to secure the side panels to the center panel.

20. A composite construction for a door or the like cornprising a generally flat-sided rectangular center panel of felted ligno-cellulosic material, a pair of relatively thin flat-sided rectangular side panels of felted ligno-cellulosic material disposed on either side of said center panel, said side panels being larger than said center panel in length and width so as to provide a pair of outwardly-protruding relatively thin generally parallel spaced flanges along each of the edges of the main panel, a plurality of snugly-fitting elongated edge-strips of wood or the like adhesively secured intermediate said flanges and forming a generally continuous recessed frame or border for the door, and an insert-block of wood or the like adhesively secured within a peripheral notch in said center panel and in juxtaposition to one of the side edge-strips, said insertblock being adapted to receive a lock element or the like, said side panels and flanges being fully impregnated with a hardened-in-situ thermo-setting resinous binder thereby to provide relatively hard outer surfacing for the door and to provide relatively strong supporting surfaces for the edge-strips, said resinous binder also serving adhesively to secure the side panels to the center panel.

21. A method of making a composite door or the like which comprises forming a generally rectangular flat-sided center panel of felted ligno-cellulosic material, forming a pair of relatively thin generally rectangular tlat-sided side panels of felted ligno-cellulosic material, said side panels being somewhat greater in length and width than the center panel, positioning about said center panel a generally continuous rectangular frame formed of elongated edgestrips of wood or the like, the length and width of the center panel and frame being equal to the length and width of the side panels, coating both sides of each of said side panels with a thermo-setting resinous binder in liquid form, positioning the coated side panels on either side of the main panel and frame, and subjecting the assembly to the action of heat and pressure thereby to cause the binder to fully impregnate the side panels and to harden-in-situ; the hardened-in-situ binder also serving adhesively to secure the impregnated side panels to the center panel and to the frame.

References Cited in the file of this patent UNITED STATES PATENTS 406,618 Benedict July 9, 1889 526,732 Norcross Oct. 2, 1894 (Other references on following page) 13 14 UNITED STATES PATENTS Shields sNov.17, 629,448 Leaver July 2s, 1899 f Se ePt- 0 656,741 Leaver Aug- 28, 1900 2,399,124 Kahf -f APF- 23, 1946 1,861,849 Frobsher June 7, 1932 FOREIGN PATENTS 1,863,800 Loetscher 1,911,374 Loetscher 2,033,884 Davidson 5 1- 1111412 561,879 Great Britain June s, 1942 Mar. 10, 1936 

